ISSN 0373-5680 Rev. Soc. Entomol. Argent. 60 (1-4): 69-72, 2001

Description of the eggs of Curicta bonaerensis (Heteroptera: )

LOPEZ RUFf Monica* y Pablo J. PEREZ GOODWYN** * Departamento Cientifico de Entomologia, Museo de La Plata, Paseo del Bosque. 1900 La Plata, Argentina; e-mail: [email protected] ** Instituto de Limnologia "Dr. Raul A. Ringuelet", CC 712.1900 La Plata, Argentina; e-mail: [email protected]

• ABSTRACT. Eggs are described based upon direct observation and scanning electron micrographs. Eggs bear 12-13 respiratory horns forming a crown each one ending in a plastron structure, which continues inside them and deve­ lops under the chorion. Three micropyles and a complex chorionic hydropyle are found. Aeropyles are found on allover the surface of the eggs on the tip of tubercles, scattered all over the surface of the eggs, except on the hydropyle, in­ side the horn crown, and in a belt surrounding it. The morphology of the eggs of this species fits the descriptions given for other Nepidae. The egg laying habit of this species is endophytic, a behavior that was thought to be restricted to Ranatri nae genera.

KEY WORDS. Egg. Chorion. Heteroptera. Nepidae. Curicta .

• RESUMEN. Descripcion de los huevos de Curicta bonaerensis (Heterop­ tera: Nepidae). Los huevos estan descriptos sobre la base de la observacion directa y las fotografias del MEB. Se observaron entre 12 y13 cuernos res­ piratorios formando una corona, cada uno de ellos finalizando en una es­ tructura de plastron, en el pedunculo se continua por dentro y se desarrolla por debajo del corion. Se encontraron tres micropilos y un hidropilo corio­ nico complejo. Se observaron aeropilos en el extremo de tuberculos distri­ buidos en toda la superficie de los huevos, excepto en el hidropilo, dentro de la corona y del cinturon que la rodea. La morfologia del huevo de esta especie coincide con la de las descriptas para otros Nepidae. El habito de postura es endofitico, conducta aparentemente restringida a los generos de Ranatrinae.

PALABRAS CLAVE. Huevo. Corion. Heteroptera. Nepidae. Curicta.

INTRODUCTION this family is scarce, particularly regarding Neotro­ pical taxa (Wiley, 1924; McPherson & Packauskas, Two Nepidae genera are recorded from Argen­ 1987; Keffer et al., 1994), even though there tina: Ranatra Fabricius, and Curicta Stal, the for­ are excellent general works (Cobben, 1968; mer one with seven species, the latter with four. Hinton, 1961,1969). Description of chorion Curicta bonaerensis (Berg) is a small waterscorpion through SEM was carried out on Naucoridae, usually found in low number, inhabiting Buenos Belostomatidae, and European Nepidae (Baker, Aires and Entre Rlos provinces, as well as Uru­ 1987; Lopez Ruf,1989; Wichard et al.,1995; guay (Keffer, 1996; Bachmann, 1998). Sites & Nichols, 1999). Eggs of Curicta, based on C. bonaerensis are described here for the Literature concerning eggs and laying habits of first time.

69 Rev. Soc. Entamal. Argent. 60 (1-4), 2001

MATERIAL AND METHODS RESULTS

Specimens of C. bonaerensis were collected in Egg description. Subeliptical with a subapical Punta Lara (Ensenada District, Buenos Aires provin­ crown of 12 to 13 plastron-bearing horns (Fig. 1). ce) in a permanent water body around 500 meters With an aft of the posterior pole- a circular hy­ away from the shore of the Rio de la Plata (34° 47' 5; dropyle (205 - 216 urn) (Fig. 2). Light brown 58° 01' W). The area sampled was usually covered when alcohol fixed, white when recently laid. by floati ng vegetation and shaded by a dense forest. Surface granulose when observed through light Mature eggs were taken from dissected fernale binocular stereoscope. Range: Length excluding oviducts (N= 8) and from endophytic eggs laid in horns: 1.52 - 1.56 mm, width: 0.54 - 0.52 rnm laboratory (N= 3). Adult specimens were kept in (ovarian eggs measured). 500 cm3 containers with Spirodela sp. (Lernna­ ceae) as substraturn. Material was extracted from Horns. 51 ightly tapered towards their blunt ethanol fixed females and since the eggs were apex. Range: Length: 0.86 - 0.97 mrn (Fig. 3), slightly collapsed, they were placed in glacial width near plastron: 17.20 urn. Apical respiratory acetic acid for a few minutes. They were then plastron (Fig. 4) developed on about 1/3 of the kept in Bouin fixing fluid in order to keep their horn length (362.16 - 378.37 urn), The plas­ original shape. Eggs were rinsed with an ultraso­ tron-bearing portion is slightly th icker than the nic cleaner for 15 minutes submerged in a mixtu­ rest of the horn. Plastron consists in a highly per­ re of 70% ethanol, 20

Fig. 1: Egg general view, inserted in leaf. Scale: 1.5 mm Fig. 2: Hydropyle. Scale: 100 urn

Fig. 3: Horns, general view. Scale: 100 urn Fig. 4: Horns, detail of the beginning of the plas­ tron-bearing portion. Scale: 50 /-lID

70 LOPEZ RUF, M. and P. PEREZ GC)ODWYN. Description eggs Curicta bonaerensis

Fig. 5: Plastron, detail. Scale: 5 J.1m Fig. 6: Transverse section of horn through plastron portion. Scale: 10 urn

Fig. 7: Transverse section of horn through portion wit­ Fig. 8: Micropyles. Scale: 100 um hout plastron. Scale: 10 urn

Fig. 9: Chorion surface, detail. Scale: 50 urn Fig. 10: Transverse section of chorion with bifurcate aeropyle and underlying plastron. Scale: 10 urn

of trabecules. Shown in transverse section (plas­ communication (horn wall thickness: 4.54 J.1m, tron thickness: 3.30J.1m) (Fig. 6) the plastron ho­ core approximate diameter: 14.60 J.1m) (Fig.7). les communicate to the inner part of the horn where a meshwork is developed, described as Chorion. Immediately below the horn crown a "core" by Hinton (1961) for Nepa cinerea Linne. tubercle bearing three micropyles (Fig. 8) is obser­ A section through the part of the horn without ved. Shortly below the micropyles, the chorion is plastron shows that the meshwork continues covered with tiny tubercles (approximately 5 J.1m along the core of the horn without any external high and 6.45 - 8.60 J.1m wide), each one located

71 Rev. Soc. Entomol. Argent. 60 (1-4), 2001 on the centre of the track of the follicular cell (ap­ ACKNOWLEDGEMENTS proximate diameter 15.00 - 23.60 urn) bearing the aeropyles (Fig. 9). Some aeropyles are bifurcated We are grateful to Dr. A. O. Bachmann, Dr. A. (Fig. 10). In transverse section the plastron (12.40­ L. Estevez and Prof. M. Perez Goodwyn for their 12.80 urn thick) is developed under the chorion helpful comments on the' manuscript. (4.00 - 5.00 urn thick) (Fig. 10). No aeropyles were observed in the centre of the horn crown (diarneter: 23.43 urn) and immediately under it (a belt about LITERATURE CITED 108 urn wide) (Fig. 8). Some endophytic eggs of C. bonaerensis depo­ BACHMANN, A. O. 1998. Heteroptera acuaticos. sited by females in laboratory were observed in In: MORRONE, j. j. & S. COSCARON (eds.), Biodi­ Spirodela sp. as substratum. When laid, onlv the versidad de Artr6podos Argentinos, Ediciones horn crown is seen and the egg axis is slightly tilted, Sur, La Plata, pp. 163-180. thus allowing the crown to be parallel to the floa­ BAKER, G. T. 1987. Morphology of the chorion of ting line (Fig.l). The aeropyle zone begins diagonal Belostoma lautariurn (Stal) (: Belos­ to the egg longitudinal axis, possibly following the tomatidae). Bull. Zool. 54: 229-231. floating line and the plant epidermis. It is worth COBBEN, R. H. 1968. Evolutionary trends in Heteropte­ noticing that this water plant was the only availa­ ra. Part I. Eggs/ architecture ofshell; gross embryo­ ble substratum for the female to lay its eggs. logy and eclosion. Wagenigen, The Netherlands. HINTON, H. E. 1961. The structure and function of the egg-shell in the Nepidae (Hemiptera). }. DISCUSSION Ins. Physiol. 7: 224-257. HINTON, H. E. 1969. Respiratory systems of Hinton (1961) described the eggs of several ne­ egg shells. Ann. Rev. Ent. 14: 343-368. pid species and concluded that the structure and KEFFER, S. L. 1996. Systernatics of the new world wa­ number of respiratory horns could be useful for ge­ terscorpion genus Curicta Stal (Heteroptera: Nepi­ nera identification, even though he found striking dae).). New York Entomol. Soc. 104(3-4): 117-215. variations between species and even between indi­ KEFFER, S. L., S. S. TAYLOR, & j. E. MCPHERSON. 1994. viduals. Eggs of C. bonaerensis borne 12 to 13 Laboratory rearing and description of inmature horns, very similar to those of N. cinerea, except for stagesof Curicta scorpio (Heteroptera: Nepidae). the slight widening of the plastron-bearing portion of Ann. Entomol. Soc. Am. 87(1): 17-26. the horn that was found in C. bonaerensis. No ano­ LOPEZ RUF, M. L. 1989. Los huevos de algunas espe­ malous horns were found probably due to the few cies de los generos Pelocoris y Ambrysus (Hete­ eggs observed. Hinton (1969) described different roptera Lirnnocoridae). Limnobio« 2(10): 720-724. kinds of plastrons and Cuticta egg plastron seems to Mc PHERSON, j.E. & R. l. PACKAUSKAS. 1987. Life be a good example of coalescence of holes. history and laboratory reari ng of Nepa apicu­ As Hinton (1961) stated for the described ne­ lata (Heteroptera: Nepidae), with descriptions pid species, aeropyles are absent in the centre of of inmature stages. Ann. Entomol. Soc. Am. the horn crown and in the hydropyle. 80: 680-685. The rnorphology of the egg of C. bonaerensis SITES, R. & B. j. NICHOLS. 1999. Egg architecture of agrees with descriptions given for other Nepinae. Naucoridae (Heteroptera): Internal and exter­ Its egglaying had however, differs from that of the nal structure of the chorion and micropyle. rest of the described Curicta species (Wiley, 1924; Proc. Entomol. Soc. Wash. 101 (1): 1-25. Keffer et al., 1994; McPherson & Packauskas, WICHARD, W., W. ARENS & G. EISENBEIS. 1995. Atlas zur 1987), it is also the only Nepinae which inserts Biologie der Wasserinsekten. G. Fischer Verlag. the eggs in leaves, a behaviour that was recorded WILEY, G. O. 1924. On the biology of Curicie dra­ only for Ranatrinae species (Cobben, 1968; Hin­ kei Hungerford (Heteroptera: Nepidae). Ent. ton, 1961). Nevertheless Spirodela sp. could not News. 192: 324-331 . be the only substratum chosen in natural condi­ tions. The position of the laid egg would fit the description of endophytic Ranatra eggs (Hinton, Recibido: 9-XI-1999 1961 ). Aceptado: 30-1-2001

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